Effects Of A7nACh Receptor Inhibition Of RRDA In Neonatal Rat In Pregnancy Smoking

Background Smoking addiction has become a social problem that can not be ignored, and tobacco has a negative impact not only on smokers, but also on the surrounding crowd and their progeny. Nicotine exposure during pregnancy can result in great harm to the fetus such as deformity, Intrauterine hypoxia, infant of low-birth weight, congenital central hypoventilation syndrome (CCHS), central respiratory rhythm disturbance(CRD), sudden infant death syndrome(SIDS) etc. Nicotine is the main alkaloid in cigarettes, and it plays a key role in central respiratory abnormalities. The stable rhythmic respiration plays an important role in maintaining normal life activities. Therefore, it is important to make clear the effect of nicotine in the respiratory center. In order to further clarify the inhibitory effect of nicotine exposure on bulbar respiratory center of offspring during pregnancy, and provide new ideas and experimental basis for the prevention and treatment of related diseases.Objective To observe the rhythmic respiratory discharge, brain a7nAChR protein levels and gene expression changes in pregnancy smoking exposed offspring. Our study was going to study the mechanism of a7nAChR in prenatal smoking exposure causes respiratory depression in progeny.MethodsHealthy Sprague-Dawley(0-3days) rats were randomly divided into control and experimental groups. The control groups were normal feeding. The experimental groups, in addition to the normal feeding, were smoked for30minutes at8:00a.m. and8:00p.m. every day. The process was continued from the moment of conception to childbirth. 1. Roles of a7nAChR agonist acetylcholine (ACh) and its antagonist Alpha-bungarotoxin (α-BGT) on basic rhythmical respiration discharge activities in the medullary slice of prenatal smoking neonatal rats.Sprague-Dawley rat medullary slice was made. It included the medial region of the nucleus retrofacialis (mNRF) with the hypoglossal nerve rootlets retained. The slices were perfused with artificial cerebrospinal fluid which equilibrium with carbogen (95%O2and5%CO2). Rhythmic respiratory discharge activity (RRDA) of slices was recorded by using a suction electrode.36slices were divide six equal groups:the group1is control group, the normal neonatal rat slices were perfused with ACSF; the group2is alcohol group, prenatal smoking neonatal rat slices were perfused with ACSF; in group3, the normal neonatal rat slices were perfused with ACSF which dissolved in ACh (10μmol/L);the group4is prenatal smoking neonatal rat slices were perfused with ACSF which dissolved in ACh (10μmol/L); the group5, the normal neonatal rat slices were perfused with ACSF which dissolved in α-BGT (10μmol/L); the group6,prenatal smoking neonatal rat slices were perfused with ACSF which dissolved in α-BGT (10μmol/L).2. Using Western Blot technology to research a7nAChR protein level in prenatal smoking neonatal rats slices.3. Using qRT-PCR technology to research a7nAChR mRNA expression level in prenatal smoking neonatal rat slices.Results1. Control group and experimental group slices discharge were stability without attenuation in60min, and the experiment model were stable and reliable. Experimental group slices discharge was weaker than control group,α7nAChR agonist ACh could excite slices discharge of the two groups, and Control group excited effect was stronger than the experimental group, a7nAChR antagonist α-BGT had inhibitory effect on slices discharge of the two groups, while Control group inhibitory effect was stronger than the experimental group. 2. Western Blot results show that, prenatal smoking down regulated a7nAChR protein expression in neonatal rat medulla oblongata slices.3. qRT-PCR results show that, prenatal smoking down regulated a7nAChR mRNA expression in neonatal rat medulla oblongata slices.Conclusions1. Prenatal smoking depresses rhythmic respiratory discharge activity in the medullaly slice, inhibits the activity of a7nAChR and down regulates the protein and mRNA expression of a7nAChR.2. Downregulating the a7nAChR and its mRNA expression is a perhaps mechanism of prenatal smoking depresses rhythmic respiratory discharge activity in the medullaly slice of neonatal rats.